Pakistan has been the Afghan Taliban’s closest friend for decades. It was Islamabad that helped give birth to the Taliban in the early 1990s – as a way to give Pakistan “strategic depth” in its rivalry with India. What’s gone wrong?Pakistan carried out air strikes on Afghanistan’s major cities overnight, officials in Islamabad and Kabul said on Friday, escalating months of border clashes between the Islamic neighbours. The air and ground strikes, which hit Taliban military posts,...